Method for manufacturing selfsupporting coils



June 6, 1967 M KEON ETAL 3,323,200

METHOD FOR MANUFACTURING SELF-SUPPORTING COILS Filed May 19, 1964 \IVVVVVVVVV FIG.2

AAAAAAA FIGZ) FIGQ4 INVENTORS PATRICK E. McKEON WAYNE E.NEESE BY 7 '7 y/azfiww ATTY.

United States Patent 3,323,200 METHOD FOR MANUFACTURING SELF- SUPPORTING COILS Patrick E. McKeon and Wayne E. Neese, Chicago, Ill., assignors to Automatic Electric Laboratories, Inc., Northlake, 111., a corporation of Delaware Filed May 19, 1964, Ser. No. 368,516. 9 Claims. (Cl. 29-15557) This invention relates to the manufacture of self-supporting coils which can be used for example as resistance windings or windings of an electromagnetic device.

Heretofore, the above type coils, regardless of how they were used, were manufactured in a number of ways and although resulting in an acceptable end product, they had drawbacks and did not lend themselves to high. production rate operation.

One method of manufacture involved the windings of a coil on a paper sleeve that was placed over a split mandrel. Although satisfactory in most respects this technique re quired a permanent sleeve to support the coil which adversely affected an electromagnetic device using the coil due to the reluctance induced between the core and winding. In addition the mandrel was costly and required adjustment and only one coil at a time could be wound.

Another method used is what is known in the industry as stick winding. Although the method lent itself to rnulticoil winding it required a permanent sleeve to support the coils and, in addition a thin layer of paper separating each layer of the coil. The paper was fed by special apparatus and added to the cost of the machine and indirectly to the cost of the coils. f

The present invention has for its principal object providing a simplified method for manufacturing self-supporting coils.

Another object of the invention isto provide a process for manufacturing self-supporting coils whereby a standard coil winding machine can be used. I

Still another object of the invention is to provide a process for manufacturing self-supporting coilswhereby an electromagneticdevice-using the coils will'be more efficient.

A feature of the process according to the' invention is that a permanent support forth'e' coil is eliminated.

This is achieved by employing a heat shrinkable sleeve which is made of a plastic material and which upon being heated shrinks away from the'coil allowing for its removal. According to one embodiment, the sleeve used features spaced peripheral embossed sections which function as spool heads and thereby provide support to the successive turns of wire of the coil. According to another embodiment, the sleeve is made into segments of lengths the same as the coil and used in combination with individual spool heads. The latter, according to a preferred embodiment is made of molded Teflon or Delrin material so asto be heat resistant. This makes them usable over and over again.

' Therefore the first step of the process according to the invention is slipping the heat shrinkable sleeve or sle'eve segment'on'the arbor or mandrel of the machine. When using the sleeve segments the spool heads are used to separate adjacent ones and consequently the two must be slipped over the mandrel concurrently. Following this step the wires are wound on the sleeve or sleeve segments as the case may be. I

The step which follows depends on whether the wires are merely enameled or enameled and coated with a selfbonding adhesive. If the wires are enameled then the next step is impregnating the wound coil with a thermal setting plastic material; if the wires are both enameled and coated with a bonding adhesive then, however, the next 'sents one embodiment and sleeve segments 35 of FIG.

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step is heating the assembly to activate the coating. Hereafter the mandrel is removed from the sleeve or sleeve seg ment and the remaining assembly is heated to the shrinkable temperature of the sleeve material. Upon removing the shrunken sleeve the coils become completely selfsupporting.

These and other objects and features of the invention Will become apparent upon making a perusal of the following detailed explanation of the process which makes reference to the accompanying drawings of which:

FIG. 1 is a front view of a loaded mandrel according to the invention. 7

FIG. 2 is a view in perspective having a cutaway portion showing of a mandrel with spool heads and shrinkable sleeve segments mounted on it.

FIG. 3 is a front view of a winding wound on a heat shrinkable sleeve prior to being heated.

FIG. 4 is a view in perspective showing the heat shrinkable sleeve shown in FIG. 3, after it is heated to its shrinkable sleeve.

Referring now to the drawings, FIG. 1 illustrates an assembly produced by the method of the invention. It includes a coil winding machine mandrel 10, a heat shrinkable sleeve 15 with embossed sections 25, and two individual coils 20. It can be appreciated that the number of coils produced at a time is not limited to two but can be any number so long that the machine is large enough for the mandrel.

The mandrel used can be a standard type constructed of steel and round in cross-section or it can be special and be of another shape, as for example, mandrel 10 which includes a slot 11 for receiving projection 32 of spool heads 30. The advantage of this design will bediscussed subsequently.

According to the invention sleeve 15 of FIG. 1 repre- 2 represents another embodiment. Which is used is a matter of choice depending. on the situation and at best may depend on the size coil desired. Sleeve 15 may be more desirable where the coil consists of only a few turns and sleeve segments 35 where the coils consists of many turns.

The material of which the sleeve 15 or sleeve segments 35 are made in a composition that can be molded and that is shrinkable to 50% of its manufactured size upon being heated to a temperature of 250 F. Furthermore, it has high dielectric strength, it is tough, abrasive and corrosive resistant all of which insures the reliability of the part on which it is associated with or used on..It is commercially available in a variety of sizes and shapes, though when used with a mandrel must be tubular shape.

While normally the material is shrunk onto another part, the invention resides in the reverse of this and its particular application in the manufacture of air core coils. Instead of making the sleeve permanent it is reheated to its melting point, remolded and used again.

Sleeve 15 includes peripheral embossed sections 25 that are formed integrally with the sleeve and serve as supports orspool heads for the coils. Upon being subject to heat the sleeve-as well as the embossed sections pull away (shrink) from the windings leaving individual self-supporting coils.

Sleeve segments 35 are used with spool heads 30 which are separate pieces, preferably made of Teflon or Delrin material. Each of the spool heads' includes apertures 36'through which the mandrel 10' extends and counterbored sections 40 and 41 which receive the ends of the sleeve segments. The aforementioned projection 32 projects into slot 11 whereby relative movement between the spool heads and the mandrel is restricted.

Restriction of relative movement is due to the fact that when the outside diameter of the sleeve segment is on the high side of its tolerance the ends thereof will exert pressure against a surface of the embossed section. Since relative movement of the spool heads is controlled the sleeve segments are also controlled. Where the outside diameter of the sleeve segment is on the low side of the tolerance then there is enough friction between the sleeve segments and the mandrel to prevent relative motion. Anything in between the two extremes will result in sufficient combined friction between the sleeve segments and a surface of the embossed sections and the sleeve segments and the mandrel to prevent relative movement.

The wire used in either one of the embodiments mentioned can be the enamel insulated wire or the enamel insulated wire with a self-bonding adhesive coating. Both types are commercially available. Which is used is again a matter of choice depending on the facilities available for the manufacture of coils. Where the uncoated enameled'wire is used then the wound coil must be impregnated with a bonding material otherwise it would not be self-supporting. The bonding material can be the self-curing type or a thermal-setting type, however, both require heat before they function as an effective bonding agent between turns of wires.

The method of manufacture thus according to one embodiment involves as the first step the placing ofsleeve 15 on mandrel 10. The operator then places this assembly into a coil winding machine which should preferably be equipped with one or more rollers for guiding the wires onto the sleeve. After the coils are wound the assembly is removed from the machine and impregnated with a bonding material. If a thermal-setting type bonding ma- 7 terial is used then impregnation is followed by a curing operation which involves heating the assembly to a temperature of approximately 240 F. Next mandrel 10 is removed and the remaining assembly reheated, preferably by inserting it into an oven, to the heat shrinkable temperature of the sleeve material, which under normal conditions is'300" F. for one-half hour duration. The shrunken sleeve is then removed from the assembly leaving finished self-supporting coils.

Where sleeve segments 35 in combination with spool heads 30 are used in the method of manufacture then the first step involves the placing of both the sleeve segments and spool heads on the mandrel so that one spool head separates adjacent sleeve segments. Since the spool heads are preferably made from heat resistant material they do not shrink and are removed simultaneously with the shrunken sleeve segments. The spool 'heads can be used over and over again to reduce the cost of the method.

Where the self-bonding material is used then the impregnating step in the above method is not necessary.

The coils produced from the method of the invention could be used to reduce the size of relays such as for example reed relays. This would be consistent with the present emphasis on making relays in general smaller size. On the other hand, coils with a larger number of turns can be used in a given area, making more efficient use of available space.

The invention has been described in connection with certain embodiments, however, it should be appreciated that there are still other embodiments which are within the spirit and scope of the invention as defined only by the following claims.

What is claimed is:

1. A method for making a self-supporting coil on a winding machine having a mandrel comprising the steps of:

(a) placing a separate heat shrinkable sleeve member on said mandrel temporarily for supporting said coil;

(b) winding at least one insulated wire on said sleeve member to form a coil;

(0) impregnating said coil with a bonding material;

age temperature of said sleeve member whereby said' sleeve member shrinks and separates from said coil.

2. A method for making a self-supporting coil on a coil winding machine having a mandrel comprising the steps of:

(a) placing a separate heat shrinkable sleeve member on said mandrel temporarily for supporting said coil;

(b) winding at least one insulated wire on said sleeve member to form a coil;

(c) impregnating said coil with a thermal setting bonding material;

(d) heating the assembly of step C to cure said bonding material and thereby support said coil on said sleeve member;

(e) removing said mandrel from said sleeve member;

(f) and heating the assembly of step (e) to the shrinkage temperature of said' sleeve member whereby said sleeve member shrinks and separates from said coil.

3. A method for making a self-supporting coil on a coil winding machine having a mandrel comprising the steps of:

(a) placing a separate heat shrinkable sleeve member on said mandrel temporarily for supporting said coil;

(b) winding at least one Wire, having a self-bonding adhesive coating, on said sleeve member to form a coil;

(c) heating the assembly of step (b) to activate said adhesive coating and thereby form a bond between turns of said wire;

(d) removing said mandrel from said sleeve member;

(e) and heating the assembly of step ((1) further to the shrinkage temperature of said sleeve member to shrink said sleeve member and thereby form a selfsupporting coil.

4. A method for making self-supporting coils on a" ing material and thereby support said coils on said sleeve;

(g) removing said mandrel from said sleeve;

(h) heating the assembly of step (g) to the shrinkage temperature of saidsleeve whereby said sleeve shrinks and separates from said coils.

5. A method for making self-supporting coils on a coil winding machine havinga mandrel comprising the steps of:

(a) placing separate sleeve segments and spool heads having apertures therein on said mandrel temporarily, such that said spool heads separate adjacent sleeve segments;

(b) mounting the assembly of step (a) in said machine to prepare for winding;

(c) wind-ing insulated wires on said sleeve segments between said spool heads to form individual coils;

(d)hremoving the assembly of step (c) from said mac me;

(e) impregnating said coils with a thermal setting bonding material;

(f) heating the assembly of step (e) to cure said bonding material and thereby support said coils on said sleeve segments;

(g) removing said mandrel and said spool heads from the assembly of step (f);

(h) heating the assembly of step (g) to the shrinkage temperature of said sleeve segments whereby said sleeve segments shrinks and separates from said coils.

6. A method for making self-supporting coils on a coil winding machine having a mandrel comprising the steps of:

(a) placing a separate heat shrinkable sleeve having spaced peripheral embossed sections on said mandrel temporarily;

(b) mounting the assembly of step (a) in said machine to prepare for winding;

() Winding individual wires having a self-bonding adhesive coating on said sleeve between said embossed sections to form individual coils;

(d) removing the assembly of step (c) from said machine;

(e) heating the assembly of step (d) to activate said adhesive coating and thereby form a bond between turns of said wires of each coil;

(f) removing said mandrel from said sleeve;

(g) and heating the assembly of step (f) further to the shrinkage temperature of said sleeve to shrink said sleeve and thereby form self-supporting coils.

7. A method for making self-supporting coils on a coil winding machine having a mandrel comprising the steps of:

(a) placing sepanate heat shrinkable sleeve segments and spool heads having apertures therein on said mandrel temporarily, such that said spool heads separate adjacent sleeve segments;

(b) mounting the assembly of step (a) in said machine to prepare for winding;

(c) winding individual wires having each a self-bonding adhesive coating on said sleeve segments between said spool heads to form individual coils;

(d) removing the assembly of step (c) from said machine;

(e) heating the assembly of step (d) to activate said 4 shrink said sleeve segments and thereby form selfsupporting coils.

8. A method for making a self-supporting coil on a coil winding machine having a mandrel comprising the steps of:

(a) placing a separate heat shrinkable sleeve member on said mandrel temporarily, for supporting said coil;

(b) winding at least one insulated wire on said sleeve to form a coil;

(c) impregnating said coil with a thermal setting plastic bonding material;

(d) heating the assembly of step (c) to approximately 240 F. to cure said bonding material and thereby support said coil on said sleeve member,

(e) removing said mandrel from said sleeve member;

(f) and heating the assembly of step (e) to approximately 200 F. for approximately one-half hour to shrink said sleeve member and separate same from said coil thereby forming a self-supporting coil.

9. A method for making a self-supporting coil on a,

coil winding machine having a mandrel comprising the steps of:

(a) placing a separate heat shrinkable sleeve member on said mandrel temporarily, for supporting said coil; (b) winding wires having a self-bonding adhesive coating on said sleeve to form a coil of a predetermined number of turns; (c) heating the assembly of step (b) to 240 F. to activate said adhesive coating and thereby form a bond between turns of said Wire; (d) removing said mandrel from said sleeve member; (e) and heating the assembly of step (d) further to approximately 300 F. for approximately one-half hour to shrink said sleeve member and separate same from said coil thereby forming a self-supporting coil.

References Cited UNITED STATES PATENTS 2,988,804 6/1961 Tibbetts 29423 X 3,146,576- 9/ 196'4- Wezel 29423 X 3,182,384 5/1965 Carlson et al 29-155.57 3,190,580 6/1965 Guerin et al 242118.'3-2

JOHN F. CAMPBELL, Primary Examiner. R. W. CHURCH, J. L. CLINE, Assistant Examiners. 

1. A METHOD FOR MAKING A SELF-SUPPORTING COIL ON A WINDING MACHINE HAVING A MANDREL COMPRISING THE STEPS OF: (A) PLACING A SEPARATE HEAT SHRINKABLE SLEEVE MEMBER ON SAID MANDREL TEMPORARILY FOR SUPPORTING SAID COIL; (B) WINDING AT LEAST ONE INSULATED WIRE ON SAID SLEEVE MEMBER TO FORM A COIL; (C) IMPREGNATING SAID COIL WITH A BONDING MATERIAL; (D) REMOVING SAID MANDREL FROM SAID SLEEVE MEMBER; (E) AND HEATING THE ASSEMBLY OF STEP (D) TO THE SHRINKAGE TEMPERATURE OF SAID SLEEVE MEMBER WHEREBY SAID SLEEVE MEMBER SHRINKS AND SEPARATES FROM SAID COIL. 